A method for cultivating plants indoors, enabling the plants to strike roots into the fluid passage member, through which the culture fluid flows, has been disclosed, for example, in Patent Literatures 1 and 2. Further, the Patent Literature 2 describes that the plants are movable in one direction according to the growth of the plants. In other words, seeds or the nursery plants are arranged at the upstream side with respect to the moving direction and the sufficiently grown plants are arranged at the downstream side with respect to the moving direction. Still further, the neighboring plants are arranged to have sufficient space therebetween in order to respond to the size change associated with the growth of the plants.
Further, Patent Literature 3 discloses that the height of the light source is changed in accordance with the growth of the plants. Patent Literature 4 discloses the protection member which makes the floral buds of the plants to grow straightly erecting upright.